Abstract

We report x-ray absorption spectra at the oxygen K edge for $LaNi_{1-x}M_xO_3$ (M = Mn, Fe and Co ) for values of x spanning the entire composition range which exhibit metal-insulator transitions at critical values of x. This study clearly shows that the metal-insulator transition in the homovalent substituted series is achieved by transferring hole states from near EF to an energy position above EF due to the potential of the substituent. This is in strong contrast to hole doping, e.g., as in $La_{1-x}Sr_xMnO_3$ where states are formed within the band gap of the underlying electronic structure. The sensitivity of the O K-edge spectra to substitution confirms the large oxygen 2p admixture to states at the Fermi level due to a substantial hopping interaction strength between the transitionmetal 3d and oxygen 2p derived states in these perovskite oxides. The present results suggest that the electronic structures of these perovskite oxides are dominated by local interactions.